/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.geode.internal.offheap;

import java.util.Iterator;
import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;

/**
 * Used by tests to get notifications about the lifecycle of a 
 * MemoryAllocatorImpl.
 * 
 */
public interface LifecycleListener {

  /**
   * Callback is invoked after creating a new MemoryAllocatorImpl. 
   * 
   * Create occurs during the first initialization of an 
   * InternalDistributedSystem within the JVM.
   * 
   * @param allocator the instance that has just been created
   */
  public void afterCreate(MemoryAllocatorImpl allocator);
  /**
   * Callback is invoked after reopening an existing MemoryAllocatorImpl 
   * for reuse. 
   * 
   * Reuse occurs during any intialization of an 
   * InternalDistributedSystem after the first one was connected and then
   * disconnected within the JVM.
   * 
   * @param allocator the instance that has just been reopened for reuse
   */
  public void afterReuse(MemoryAllocatorImpl allocator);
  /**
   * Callback is invoked before closing the MemoryAllocatorImpl
   * 
   * Close occurs after the InternalDistributedSystem and DistributionManager 
   * have completely disconnected. 
   * 
   * @param allocator the instance that is about to be closed
   */
  public void beforeClose(MemoryAllocatorImpl allocator);
  
  static  void invokeBeforeClose(MemoryAllocatorImpl allocator) {
    for (Iterator<LifecycleListener> iter = lifecycleListeners.iterator(); iter.hasNext();) {
      LifecycleListener listener = iter.next();
      listener.beforeClose(allocator);
    }
  }
  static void invokeAfterReuse(MemoryAllocatorImpl allocator) {
    for (Iterator<LifecycleListener> iter = lifecycleListeners.iterator(); iter.hasNext();) {
      LifecycleListener listener = iter.next();
      listener.afterReuse(allocator);
    }
  }
  static void invokeAfterCreate(MemoryAllocatorImpl allocator) {
    for (Iterator<LifecycleListener> iter = lifecycleListeners.iterator(); iter.hasNext();) {
      LifecycleListener listener = iter.next();
      listener.afterCreate(allocator);
    }
  }
  /**
   * Removes a LifecycleListener. Does nothing if the instance has not been added.
   * @param listener the instance to remove
   */
  public static void removeLifecycleListener(LifecycleListener listener) {
    lifecycleListeners.remove(listener);
  }
  /**
   * Adds a LifecycleListener.
   * @param listener the instance to add
   */
  public static void addLifecycleListener(LifecycleListener listener) {
    LifecycleListener.lifecycleListeners.add(listener);
  }

  /**
   * Following should be private but java 8 does not support that.
   */
  static final List<LifecycleListener> lifecycleListeners = new CopyOnWriteArrayList<LifecycleListener>();
}